Breast cancer starts as a lump in the breast and this is known as primary breast cancer. In many women, primary breast cancer does not come back after treatment. However, in some women, cancer cells break away from the primary breast cancer and spread to other parts of the body through the bloodstream or lymphatic system.
These cancer cells go on dividing and form a new cancer, known as a secondary cancer or metastasis. The secondary cancer is made up of breast cancer cells. This means that, for example, a secondary breast cancer in the liver behaves as and is treated as breast cancer, not a primary liver cancer.
Secondary breast cancer may be diagnosed years after primary breast cancer. Very occasionally, for some women, secondary breast cancer is their first diagnosis of breast cancer.
Where breast cancer may spread to
If breast cancer spreads, the most common places it can spread to are the bones, lungs,liver, or occasionally the brain.This does not mean that secondary breast cancer will spread to all of these places.
Less commonly, breast cancer can spread to other parts of the body, such as the bone marrow or ovaries. Our cancer support specialists will be able to give you more information on this.
Local and regional recurrence
Breast cancer that comes back in the skin of the breast where the cancer was first removed, or in the operation scar, is known as a local recurrence.
Breast cancer may also come back in the lymph nodes in the armpit, behind the breast bone, or in the lower part of the neck. This is called regional recurrence. If cancer cells are blocking the lymph nodes in the armpit, fluid can build up in the arm causing swelling known as lymphoedema.
Local and regional recurrences are not secondary breast cancer, as the cancer has not spread to another organ in the body.
These recurrences are usually less serious than secondary breast cancer. But you will usually have tests to find out if the cancer has spread to other parts of the body.
A local or regional recurrence that hasn't spread anywhere else in the body may be treated with surgery, if possible, or with radiotherapy. Your treatment will depend on the treatments you received to remove and treat the primary breast cancer.
Symptoms of secondary breast cancer
The symptoms of secondary breast cancer depend on the part of the body the cancer has spread to. In this section we explain the general symptoms, and some of the more specific symptoms you may experience.
All the symptoms mentioned here can be caused by other conditions. But if you have any of these symptoms it's important to get them checked out by your doctor or specialist nurse. Always let them know if you develop any new symptoms, especially if they last more than a week or two.
If cancer has spread to the bones
The first symptom of this is often a nagging ache in the bone. This may become painful when you are moving around, or make it difficult to sleep. The pain tends to be there both day and night.
Aches and pains are not uncommon and can be caused by different things. But it's important to see your doctor if your symptoms continue.
Secondary breast cancer in the bones can be controlled with hormonal therapy and drugs that strengthen the bones.
Other bone problems
These are not common in women who are newly diagnosed with secondary breast cancer in the bone. But it's important to know about them.
A break in the bone (fracture)
If the cancer gradually damages the bone it may become weaker and occasionally a very weak bone can break (fracture). Treatments are usually started long before a bone is weak enough to break.
Sometimes if the cancer damages the bone it can cause calcium (a mineral stored in bones) to be released into the blood. A high level of calcium in the blood (hypercalcaemia) can cause symptoms such as feeling tired, sick, thirsty, passing more urine, being constipated or feeling confused. Hypercalcaemia can be picked up on a blood test before symptoms develop. Treatments are given to correct the calcium level and relieve any symptoms.
Spinal cord compression
Occasionally, if the secondary cancer has spread to the spine and is causing pressure on the spinal cord, this may cause symptoms. These include unexplained pain in the back, neck, or down the arm; numbness or pins and needles in toes, fingers or buttocks; unsteadiness or difficulty walking; or problems with bladder or bowel control. If you have any of these symptoms it is very important to let your cancer doctor or nurse know immediately. Spinal cord compression can be successfully treated if it is diagnosed quickly.
If cancer has spread to the lungs
The first symptoms of this may be a cough that doesn't get better or breathlessness. If cancer cells settle on the outside of the lungs, they can irritate the membranes which cover the lungs (pleura). This causes fluid to build up and press on the lungs which can make you breathless. This is called a pleural effusion. The fluid can be drained away to make your breathing easier.
Breathlessness can be frightening, but there are effective ways of managing it. When treatment - usually chemotherapy - starts to work, your breathing will improve.
If cancer has spread to the liver
Some women may have discomfort or pain in the liver, which is on the right side of the tummy (abdomen) under the ribs. Other symptoms may include feeling sick, losing your appetite, or feeling very tired and generally unwell.
Occasionally, secondary breast cancer in the liver results in a build-up of bile in the blood causing jaundice. This makes the skin and whites of the eyes become yellow and skin feels itchy.
The liver is a large organ and can still work well even when it is affected by cancer. When your treatment - usually chemotherapy - starts to work, the symptoms will improve.
If the cancer has spread to the brain
This may cause symptoms such as a headache that doesn't go away, feeling sick or being sick. These symptoms are caused by increased pressure in the brain and may be worse first thing in the morning.
Depending on the part of the brain that is affected, some women may have other symptoms. This can include feelings of weakness, pins and needles or numbness in an arm or a leg, or sometimes a seizure (fit).
It is natural to feel frightened at the thought of having a secondary cancer in the brain. However, drugs called steroids and radiotherapy are used to treat the cancer. This will get rid of the headaches and improve other symptoms.
*Information provided by Macmillan cancer support